The present invention relates to a method for entangling fiber yarns, especially carbon fiber yarns.
The entangling or twisting of bundles of yarn has been long practiced in the art as a means of compacting and unifying a yarn bundle which resists the pulling out of individual filaments during winding, knitting, weaving, etc. Twisting has also been employed as a means of decolumnizing a carbon fiber bundle which renders the bundle more adaptable to being impregnated by a matrix-forming resin as noted in the abovereferenced applications, the disclosures of which are hereby incorporated by reference herein.
One previously employed entangling apparatus, disclosed in U.S. Pat. No. 3,727,274, comprises a block in which there is formed a cylindrical bore for conducting the travel of a bundle of filamentary material therethrough. A narrow string-up slot communicates with the bore and extends to one side of the block to enable the filamentary material to be inserted into the bore. Also communicating with the bore are three fluid ports, two of which are mutually parallel and oriented tangentially relative to the bore, and the other of which is oriented radially relative to the bore. As a bundle of filamentary material passes through the bore, pressurized air or water is introduced simultaneously through the three fluid ports. The water impinges against the bundle in such manner that the bundle is opened and simultaneously interleaved to an entangled condition. For ease of fabrication, the block is formed as two segments which are clamped or screwed together, the parting line between the segments being disposed in a common plane with the longitudinal axis of the bore. A plurality of the above-described jets, mounted on a common base, handle a plurality of yarns which are being simultaneously fed.
Although such an entangling apparatus has performed successfully, room for improvement remains. For example, a common occurrence in the use of such jets is the accumulation of "trash" such as broken fibers, at the inlet end of the yarn passage. When the trash reaches the inlet end of the respective yarn passage, it is prevented from entering the passage due to the water flow emanating from such inlet end. Consequently, the trash builds up and eventually obstructs the yarn travel to such an extent that the yarn may break. This problem is of particular concern in the case of carbon yarns, which are relatively fragile. Thus, it would be desirable to be able to clear the trash without endangering the yarn or halting production. In this regard, the string-up slots employed in the previously described jets tend to become clogged with trash and must be cleaned out in what amounts to a time-consuming operation.
Furthermore, it is customary to feed hundreds of yarns simultaneously in the same plane. Thus, it is necessary to provide a like number of jets. Understandably, then, the area occupied by the jets can become quite significant and create serious space problems. It would be desirable, therefore, to reduce, to as great an extent as possible, the space occupied by the jets.
A further consideration relates to the fact that the ports disposed within the jets for conducting water to the yarn passages are quite small and thus must be occasionally cleaned. If not easily accessible, a cleaning operation can be rather difficult and time consuming. Therefore, it would be desirable to enable the inlet and outlet ends of those ports to be easily accessible for cleaning.
It is, therefore, an object of the present invention to provide a novel apparatus for entangling filamentary yarn, especially carbon filamentary yarn.
Another object is to provide such an apparatus in which built-up trash is easily and inexpensively cleared.
A further object is to minimize the fuzz level of the resulting yarns.
An additional object is to minimize the spacing between jets to accomodate as many yarns as possible within a given size space.
One further object is to enable the inlets and outlets of the fluid ports to be easily cleaned.
An additional object is to provide such an apparatus which involves a smaller capital investment and is of less cost to operate and maintain.